A fully automatic temperature control type concrete penetration resistance measuring device and measuring method

Abstract

The application discloses a kind of full-automatic temperature control type concrete penetration resistance measuring device and measuring method, device with numerical control device as core, supporting real-time clock unit calibration cement water instant as timing zero point, strictly aligns standard definition;Integrating temperature and humidity double-parameter control's temperature control cavity, temperature sensor inserted into sample interior, servo penetration mechanism with resistance feedforward, image quantitative water absorption mechanism with anti-fog lens and carousel type automatic needle changing mechanism;Method uses temperature and humidity decoupling control based on absolute moisture content, retains material natural hydration heat release characteristics, through hydration temperature rise model and resistance-hydration degree correlation model joint prediction setting process, adaptive scheduling detection time, automatically complete bleeding removal, needle changing, uniform speed penetration and data processing.The timing reference of the application is compliant, high in environmental simulation accuracy, good in test repeatability, high in detection efficiency, and suitable for concrete setting time determination in the fields of engineering detection and building material research.

Description

Technical Field

[0001] This invention relates to the field of highway engineering testing equipment technology, specifically to a fully automatic temperature-controlled concrete penetration resistance measuring device and method. Background Technology

[0002] The setting time of cement concrete is a core indicator for evaluating its workability and determining the construction window period. The current "Test Procedures for Cement and Cement Concrete in Highway Engineering" JTG3420—2020 stipulates that the setting time is determined by the penetration resistance method: mortar from the concrete mixture is sieved and placed into a standard mold. During the curing process, a penetration needle is used to press the mortar into the mold at specified time intervals, and the penetration resistance is measured. Initial setting is determined when the penetration resistance reaches 3.5 MPa, and final setting is determined when the penetration resistance reaches 28 MPa.

[0003] Existing penetration resistance testing equipment is mostly manual or semi-automatic at room temperature, which has several limitations in engineering testing and materials research and development. Firstly, environmental control capabilities are insufficient. Most equipment relies solely on ordinary forced-air constant temperature chambers for air temperature control, resulting in poor temperature uniformity and a general lack of humidity control, making it impossible to simulate complex construction environments such as high-temperature dryness and low-temperature high-humidity conditions. Furthermore, it can only monitor the chamber air temperature, failing to obtain the actual hydration temperature inside the sample. The test conditions have a low degree of matching with the engineering site, limiting the guidance of test results for on-site construction. Secondly, human error is significant during testing. Water removal relies entirely on operator experience, with no standardized wiping force or duration, easily leading to residual water causing lower readings or excessive wiping disturbing the surface mortar, resulting in higher readings. The penetration process is mostly driven by ordinary motors, causing large fluctuations in rate when resistance changes, and is prone to excessive penetration due to motor inertia. All stages, from mold positioning and needle changing to reading and recording, require manual intervention, resulting in high labor intensity. The relative deviation of parallel sample test results is usually above 10%, with significant data dispersion. Third, the testing sequence is rigid and unreasonable. Most devices use the start time of device startup as the starting point, which deviates from the zero point of water addition defined in the standard. The final result needs to be manually converted and corrected. Moreover, fixed time intervals are generally used for testing. In the early stage of hydration, when it is far from the condensation point, the test is redundant and inefficient. In the later stage of hydration, when it is close to the condensation point, it is easy to miss the key inflection point. It is difficult to accurately capture the initial and final condensation times, and it is impossible to balance the testing accuracy and operating efficiency. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a fully automatic temperature-controlled concrete penetration resistance measuring device and method. Using the standardized cement-water mixing time as the zero point, the device automatically completes water removal, needle replacement, penetration, and data processing in a temperature- and humidity-controlled curing environment. Furthermore, it utilizes the combined parameters of sample internal temperature rise and penetration resistance to predict the setting process and adaptively schedule the testing time, thus balancing test accuracy and efficiency.

[0005] This invention is achieved through the following technical solution:

[0006] A fully automatic temperature-controlled concrete penetration resistance measuring device includes a frame, a temperature control component, an automatic penetration component, an automatic needle changing component, an automatic water absorption component, a standard test mold component, and a numerical control device.

[0007] The temperature control component is located inside the frame and includes a temperature control cavity and a refrigeration unit, a heating unit, a humidification unit and a dehumidification unit disposed in the temperature control cavity;

[0008] The standard test mold assembly is located in the temperature control cavity and includes a standard penetration test mold, a test mold base and a sample internal temperature sensor. The sample internal temperature sensor is used to be inserted into the sample to collect the sample internal temperature.

[0009] The automatic insertion assembly, the automatic needle changing assembly, and the automatic water absorption assembly are all located on the upper part of the frame and above the temperature control chamber; the automatic needle changing assembly is equipped with multiple sets of standard insertion needles with different cross-sectional areas.

[0010] The CNC device is electrically connected to the temperature control component, the standard test mold component, the automatic penetration component, the automatic needle changing component, and the automatic water absorption component, respectively. It is used to determine the detection time based on the internal temperature data of the sample and the measured penetration resistance data, and to control the automatic water absorption component to remove the water seeping from the sample surface, the automatic needle changing component to switch the standard penetration needle, and the automatic penetration component to perform the penetration detection at each detection time.

[0011] Optionally, the temperature control assembly further includes a temperature and humidity sensor and a heat insulation layer, wherein the temperature and humidity sensor is disposed inside the temperature control cavity, and the heat insulation layer covers the outside of the temperature control cavity;

[0012] The cooling unit is a semiconductor refrigeration chip, and the heating unit is an electric heating assembly. Both the semiconductor refrigeration chip and the electric heating assembly are attached to the outer wall of the temperature control cavity and are located between the temperature control cavity and the heat insulation layer.

[0013] The humidification unit is an ultrasonic humidification unit, and the ultrasonic humidification unit and the dehumidification unit are located on the side wall of the temperature control cavity.

[0014] Optionally, the standard mold assembly further includes an electromagnetic adsorption device. The standard penetration mold is positioned on the mold base, the electromagnetic adsorption device is fixed to the mold base and electrically connected to the CNC device, and the bottom of the standard penetration mold is made of ferromagnetic material. When the electromagnetic adsorption device is energized, it adsorbs and fixes the standard penetration mold to the mold base.

[0015] The measuring device further includes a sealing and moisturizing component, which includes a sealing cap and a moisturizing cotton. The sealing cap is used to cover the top of the standard penetration mold during the testing interval, and the moisturizing cotton is located inside the sealing cap.

[0016] Optionally, the automatic penetration assembly includes a drive motor, a displacement slide, a penetration probe, and a pressure sensor;

[0017] The drive motor is a servo motor and is located on the upper part of the frame;

[0018] The penetration probe is positioned below the drive motor via the displacement slide and is connected to the drive motor in a transmission manner.

[0019] The displacement slide table drives the penetration probe to move horizontally to switch the measuring point;

[0020] The pressure sensor is located at the lower end of the penetration probe;

[0021] The automatic needle changing assembly further includes a needle changing turntable and a needle changing drive unit. The needle changing turntable is rotatably mounted on the frame, and the needle changing drive unit is connected to the needle changing turntable in a transmission manner.

[0022] Multiple sets of the standard insertion needles are arranged at circumferential intervals along the needle changing turntable;

[0023] After the needle changing turntable is rotated, the standard penetration needle located at the working position connects with the penetration probe and moves downward with the penetration probe, while the other standard penetration needles remain in a avoidance position.

[0024] Optionally, the automatic water absorption assembly includes a miniature water pump, a water-absorbing sponge head, a water-absorbing drive rod, and an image acquisition module. The water-absorbing drive rod is a lifting and telescopic structure, the water-absorbing sponge head is located at the lower end of the water-absorbing drive rod, and the miniature water pump is connected to the water-absorbing sponge head.

[0025] The image acquisition module is located on the upper part of the frame, facing the sample surface inside the standard penetration mold, and is electrically connected to the CNC device. The lens of the image acquisition module is equipped with an anti-fog unit.

[0026] Optionally, the CNC device includes a control module, a touch panel, a pressure digital display, a temperature and humidity digital display, a real-time clock unit, a storage unit, and a data interface, wherein the touch panel, the pressure digital display, and the temperature and humidity digital display are disposed on the front of the frame;

[0027] The real-time clock unit is used to calibrate the test time reference with the time of cement mixing as the zero point; the storage unit is electrically connected to the control module, and the data interface is connected to the storage unit.

[0028] A fully automatic temperature-controlled concrete penetration resistance measurement method, implemented using a fully automatic temperature-controlled concrete penetration resistance measurement device, includes the following steps:

[0029] S1. The sieved mortar sample is placed into the standard penetration test mold and positioned and fixed. The internal temperature sensor of the sample is inserted into the sample, and the time of mixing cement and water is taken as the zero point of timing.

[0030] S2. Adjust the ambient temperature and humidity inside the temperature control chamber to the set value and maintain it stable, while collecting the internal temperature data of the sample.

[0031] S3. Determine the timing of each test based on the internal temperature data of the sample and the measured penetration resistance data, and execute the test sequentially at each testing time:

[0032] Remove the oozing water from the sample surface;

[0033] Select a standard penetration needle with a corresponding cross-sectional area based on the measured penetration resistance.

[0034] The driving penetration probe drives the selected standard penetration needle to penetrate the sample at a constant speed and collects the penetration resistance.

[0035] Move to the next measurement point;

[0036] S4. Fit the resistance-time curve based on the time and penetration resistance data obtained from each test, and calculate the initial setting time and final setting time.

[0037] Optionally, in step S2, the target absolute moisture content is determined based on the set target temperature and target relative humidity;

[0038] During temperature regulation, the target absolute moisture content is used as the control benchmark. The current saturated vapor pressure and corresponding relative humidity are determined based on the current temperature. The outputs of the humidification unit and the dehumidification unit are adjusted to counteract the relative humidity drift caused by temperature changes.

[0039] Optionally, in step S3, determining the detection time for each step includes:

[0040] The first test uses a dual-condition triggering method, which acquires the sample surface image and identifies the water seepage state. When the water seepage reaches the preset triggering condition, the first test is started. If the preset triggering condition is not met even after the time from the zero point of the timing has reached the preset fallback time, the first test is forcibly started.

[0041] If the number of penetration resistance data sets obtained after the first test is less than the preset number, the test will be performed at a preset fixed interval.

[0042] After the number of penetration resistance data sets reaches the preset number, a hydration temperature rise model is fitted based on the internal temperature data of the sample and the degree of hydration is determined. A correlation model between penetration resistance and degree of hydration is established. The initial setting resistance threshold and the final setting resistance threshold are substituted into the correlation model to back-calculate the corresponding setting point time. The interval of the next test is adjusted according to the remaining time from the current time to the setting point time.

[0043] Optionally, in step S3, the removal of oozing water from the sample surface includes:

[0044] Acquire a sample surface image, determine the bleed area and bleed area from the sample surface image based on grayscale segmentation, determine the bleed thickness based on the grayscale value of the bleed area and the pre-calibrated grayscale-thickness relationship, determine the bleed amount based on the bleed area and the bleed thickness, match the water absorption execution parameters based on the bleed amount, and remove the bleed water according to the water absorption execution parameters;

[0045] The uniform penetration adopts a control method that combines speed closed-loop and resistance feedforward. The speed closed-loop control is performed with the target penetration rate as the set value, and the drive output is compensated with the real-time collected penetration resistance. When the penetration depth reaches the preset switching depth, the speed closed-loop is switched to the position closed-loop and the speed is reduced until the target penetration depth is reached.

[0046] This invention integrates a bidirectional temperature control structure with automatic water absorption, automatic needle changing, automatic penetration components, and electromagnetic adsorption positioning mold components. By using a temperature and humidity controlled curing environment, a timing reference with the water addition time as the zero point, and a detection scheduling system that combines the internal temperature rise and penetration resistance of the sample, the device performs the condensation time detection process, thus balancing detection accuracy and operational efficiency. Attached Figure Description

[0047] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, but do not constitute a limitation on the embodiments of the present invention.

[0048] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0049] Figure 2 This is a circuit block diagram of the present invention.

[0050] Figure reference numerals: 1-Standard penetration test mold; 11-Moisturizing cotton; 12-Sealing cap; 13-Piercing temperature sensor; 2-Test mold base; 21-Electromagnetic adsorption device; 3-Temperature control chamber; 31-Semiconductor cooling chip; 32-Electrical heating component; 33-Insulation layer; 34-Temperature and humidity sensor; 36-Ultrasonic humidification unit; 37-Dehumidification unit; 4-Piercing probe; 41-Horizontal fine-tuning displacement slide; 42-Standard penetration needle; 43-Drive motor; 44-Needle changing turntable; 45-Needle changing drive component; 5-Miniature water pump; 51-Water-absorbing sponge head; 52-Water-absorbing drive rod; 6-CNC device; 61-Data interface; 62-Touch panel; 63-Pressure digital display; 64-Temperature and humidity digital display; 65-Control module; 7-Image acquisition module. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0052] It should also be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0053] Where there is no conflict, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0054] Example 1

[0055] This embodiment illustrates the overall hardware structure and fully automated operation process of the device, as follows: Figure 1 As shown. The device can complete the entire condensation time detection process under a set temperature and humidity environment. The detection process does not interfere with the natural hydration exothermic reaction of the sample, thus fully preserving the material's own hydration characteristics.

[0056] The device uses a rack as its main support and is divided into a detection and execution layer, an environmental control layer, and a control layer from top to bottom, with all components integrated collaboratively. The environmental control layer is located inside the rack, and its core component is the temperature control unit.

[0057] The temperature control chamber 3 is a sealed maintenance chamber. The outer wall is attached with a semiconductor cooling chip 31 and an electric heating component 32 to form a two-way closed-loop control structure for both hot and cold. Temperature and humidity sensors 34 are arranged inside the chamber, and ultrasonic humidification unit 36 ​​and dehumidification unit 37 are installed on the side walls respectively, which together form a temperature and humidity dual-parameter execution system. The outer side of the chamber is covered with a heat insulation layer 33 to block the heat and humidity exchange between the inside and outside of the chamber, thereby improving control stability and operating efficiency.

[0058] The dehumidification unit 37 may be a semiconductor condenser dehumidifier, or in other embodiments, a rotary dehumidification or desiccant circulation dehumidification structure may be used.

[0059] The standard test mold assembly is located on the bottom surface of the temperature control cavity 3, including the standard penetration test mold 1, the test mold base 2, the electromagnetic adsorption device 21, and the sample internal temperature sensor 13.

[0060] The trial mold base 2 is fixed to the bottom surface of the cavity, and the upper surface is provided with an annular positioning reference; the electromagnetic adsorption device 21 is an annular electromagnet, which is embedded in the positioning groove of the base and electrically connected to the CNC device 6.

[0061] The standard penetration test mold 1 conforms to the requirements of JTG3420—2020, with an inner diameter of 150mm and a net height of 150mm. The bottom is made of ferromagnetic material, allowing it to be attracted and fixed upon power-up after being placed on the base. Its coaxial positioning accuracy reaches ±0.5mm, and it can be easily removed and placed after power-off. The internal temperature sensor 13 is a high-precision needle-type temperature sensing element with a measurement accuracy of ±0.1℃. During use, it is inserted into the mortar sample to a depth of 15mm to 30mm, for example, 20mm. The insertion position avoids the pre-planned penetration measurement point area and the water absorption operation area, allowing for real-time continuous acquisition of natural hydration temperature rise data inside the sample.

[0062] The detection execution layer is located on the upper part of the frame, directly above the temperature control chamber, and integrates three independent execution mechanisms, all of which are uniformly scheduled by the CNC device 6.

[0063] The automatic penetration assembly includes a drive motor 43, a displacement slide 41, a penetration probe 4, and a pressure sensor.

[0064] The drive motor 43 is a servo motor with an incremental encoder. It converts the rotational motion into vertical linear motion through the transmission pair. The penetration depth is obtained in real time by the encoder feedback. The penetration zero point is calibrated at the position where the pressure sensor shows the initial reading when the penetration needle contacts the sample surface.

[0065] The displacement slide 41 is a two-dimensional electric slide in the XY direction, which can drive the penetration probe 4 to move arbitrarily in the horizontal plane and automatically plan the path to switch test points; the pressure sensor is located at the lower end of the probe to collect the resistance value during the penetration process in real time.

[0066] The automatic needle changing assembly includes a needle changing turntable 44, a needle changing drive unit 45, and three sets of standard insertion needles 42. The needle changing turntable 44 is rotatably mounted on the frame, and the needle changing drive unit 45 drives the turntable to accurately index and position. The three sets of standard insertion needles 42 are arranged at intervals along the circumference of the turntable, with cross-sectional areas of 100mm², 50mm², and 20mm², respectively, corresponding to the low, medium, and high resistance test ranges, which meet the specification size requirements. The insertion needle at the working position is coaxially connected to the insertion probe 4 and completes the insertion as the probe moves downward, while the other needles remain at a high position to avoid interference.

[0067] The automatic water absorption assembly includes a miniature water pump 5, a water-absorbing sponge head 51, a water-absorbing drive rod 52, and an image acquisition module 7. The water-absorbing drive rod 52 is an electric push rod type lifting and telescopic structure, which controls the degree of contact between the sponge head and the sample surface by pressing down; the water-absorbing sponge head 51 is located at its lower end and is connected to the miniature water pump 5 through a pipeline, which can extract the secreted water under negative pressure.

[0068] The image acquisition module 7 is vertically aligned with the sample surface. The lens is equipped with a heating and anti-fogging unit and a hydrophobic coating. With the help of a drying gas path purging, the lens surface temperature can be controlled to be 2-3°C higher than the dew point temperature inside the cavity, preventing condensation in a high-humidity environment and ensuring clear imaging.

[0069] The core of the control layer is the numerical control device 6, which is located on the front of the frame and includes a pressure digital display 63, a temperature and humidity digital display 64, a control module 65, a touch panel 62, and a real-time clock unit.

[0070] The digital display is used to show key parameters in real time, and the touch panel is used for parameter input and operation control; the real-time clock unit has its own backup power supply, so the time reference is not lost when power is lost, and it supports calibrating the cement-water mixing time as the zero point of timing, and the entire process time axis is aligned with the standard definition.

[0071] The control module 65 is the core of the device's operation, with multiple built-in control algorithms to coordinate the entire process. The device is also equipped with a data storage and output module and a sealing and moisturizing component: the data storage and output module includes a storage unit and a data interface 61, which automatically retains all test data and supports report export and traceability; the sealing and moisturizing component includes a sealing cover 12 and a moisturizing cotton 11, which closes the test mold during intermittent testing to reduce the evaporation of moisture from the sample surface.

[0072] The fully automated detection process in this embodiment is as follows:

[0073] Before the test, the mortar sieved according to the specifications was layered and put into the standard penetration test mold 1. After vibration and leveling, it was placed in the positioning reference of the test mold base 2. The internal temperature sensor 13 of the sample was inserted, and the electromagnetic adsorption was activated to fix the test mold.

[0074] The timing zero point is set by calibrating the cement-water mixing time using the touch panel. After setting the target temperature and humidity parameters, the test is started, and the device enters the automatic curing and detection state.

[0075] The initial penetration adopts a dual-condition start of "water seepage trigger + timed fallback": the image acquisition module 7 periodically acquires images of the sample surface and triggers the first detection when the water seepage reaches the set threshold; if the preset fallback time has not been reached and the detection is not triggered, the detection is forcibly started, covering low water seepage formulation scenarios.

[0076] A single detection cycle is executed sequentially: the image acquisition module acquires surface images, the control module identifies the water seepage state and matches the corresponding water absorption parameters, the water absorption drive rod drives the sponge head to press down and adhere to the sample surface, the micro water absorption pump starts to quantitatively remove the seepage water and then resets;

[0077] The needle changer drives the turntable to rotate, switching the insertion needle to match the current resistance level.

[0078] The servo motor starts and drives the penetration probe downward at a constant speed. It penetrates to the target depth within a specified time. When it approaches the end point, it automatically decelerates and buffers. The pressure sensor collects the peak resistance and uploads the data.

[0079] The displacement slide moves the measuring rod to the next measuring point, ensuring that the spacing between measuring points and the edge distance meet the specifications.

[0080] During intermittent testing, the sealing cap is automatically closed to maintain humidity. The control module combines the internal temperature rise data of the sample with the measured resistance data to jointly predict the hydration process and dynamically adjust the interval of the next test.

[0081] The entire test data is automatically stored. After the test, the resistance-time curve is automatically fitted, the initial and final setting times are interpolated, and a standard format test report is generated. The data can be exported and saved through the data interface.

[0082] Example 2

[0083] Based on the hardware structure of Embodiment 1, this embodiment details the specific implementation of the core control algorithm of the device.

[0084] All algorithms are integrated into the control module 65, which collaboratively support the automatic operation of the entire process, including temperature and humidity control, quantitative removal of oozing water, constant rate penetration detection, and adaptive scheduling of the hydration process. The control logic of each subsystem is unfolded according to the functional hierarchy as follows.

[0085] After the experiment was started,

[0086] First, complete the sample loading and timing zero-point calibration.

[0087] The concrete mixture retrieved from the site was screened to extract mortar according to the specifications. The mortar was then layered into the standard penetration test mold 1, compacted by vibration, and the surface was leveled. The mold was then placed stably in the positioning boss of the test mold base 2, and the electromagnetic adsorption device 21 was activated to adsorb and fix the test mold.

[0088] Insert the internal temperature sensor 13 of the sample into the central region of the sample to a set depth, avoiding the planned area for penetration measurement points.

[0089] The operator inputs the actual cement-water mixing time via the touch panel 62, or marks the moment water is added via the panel buttons; the system then sets this moment as the zero point for setting time. The built-in real-time clock automatically accumulates the elapsed time from midnight to the present, and the timestamps of all data in the entire process are based on this.

[0090] If the time interval between placing the sample Once the recommended initial testing duration has been reached, the system will directly enter the testing preparation process; if it is still early before midnight, the temperature and humidity control program will be started, waiting for the initial testing to be triggered.

[0091] Then it enters the temperature and humidity coupled controlled growth stage.

[0092] The control module 65 adopts a decoupled control strategy based on absolute humidity to avoid mutual interference between temperature and humidity during temperature regulation.

[0093] The control logic establishes a quantitative relationship based on Magnus's saturated vapor pressure formula: In the formula, The temperature of the chamber air is expressed in °C. This represents the saturated vapor pressure at the corresponding temperature, in kPa.

[0094] Based on the set target relative humidity Calculate the target absolute moisture content at the target temperature. : In the formula, The target temperature is expressed in °C. The default atmospheric pressure inside the chamber is 101.325 kPa (standard atmospheric pressure). The target absolute moisture content is expressed in kg / kg.

[0095] During dynamic temperature regulation, the target absolute moisture content is used. To maintain a constant control benchmark, the current saturated vapor pressure and corresponding relative humidity are calculated in real time based on the current temperature. The output power of the ultrasonic humidification unit 36 ​​and the dehumidification unit 37 are dynamically adjusted to counteract the relative humidity drift caused by temperature changes and stabilize the relative humidity inside the cavity within the set value ±5%RH.

[0096] In the engineering implementation, a table of saturated vapor pressure corresponding to each 1℃ within the range of 5℃ to 40℃ is pre-stored, and the table lookup method is used for rapid calculation to improve the control response speed.

[0097] The four execution units—cooling, heating, humidifying, and dehumidifying—adopt an interlocking and coordinated switching logic according to the operating conditions.

[0098] Under steady-state operating conditions, both the heating and humidity control units adopt PID fine-tuning mode, and the humidification and dehumidification units are interlocked to start and stop to avoid energy consumption.

[0099] Under the temperature regulation condition, the electric heating component 32 is activated first to raise the cavity temperature, and the ultrasonic humidification unit 36 ​​is activated simultaneously to compensate for humidification according to the coupling rule, so as to offset the decrease in humidity caused by the temperature rise. Under this condition, the semiconductor cooling chip 31 and the dehumidification unit 37 remain closed.

[0100] In the cooling and regulation mode, the semiconductor cooling chip 31 is activated first to reduce the cavity temperature, and the dehumidification unit 37 is activated simultaneously to dehumidify according to the coupling rule, so as to offset the increase in humidity and the risk of condensation caused by cooling. In this mode, the electric heating component 32 and the ultrasonic humidification unit 36 ​​remain off.

[0101] Through the above control strategy, the device can achieve a temperature control range of 5℃ to 40℃ with an environmental temperature control accuracy of ±1℃; and a humidity control range of 40% to 95%RH with a humidity control accuracy of ±5%RH. During the controlled curing process, the internal temperature sensor 13 of the sample continuously collects the internal temperature rise data of the sample. The system only records and calculates the data, without interfering with the hydration heat release process of the sample itself through cooling or heating, thus fully preserving the inherent hydration characteristics of different formulation materials.

[0102] A progressive adaptive scheduling strategy is adopted during the detection phase.

[0103] The initial penetration uses a dual-condition initiation mechanism of "timed backstop + water seepage trigger":

[0104] The image acquisition module 7 acquires a sample surface image every 5 minutes. When the percentage of the oozing area reaches a preset area threshold and the oozing thickness reaches a preset thickness threshold, the first penetration is triggered. The area threshold can be set in the range of 3% to 8%, for example, 5%, and the thickness threshold can be set in the range of 0.1mm to 0.5mm, for example, 0.2mm.

[0105] If it is close to the zero point of the timer If the triggering condition is not met after the preset fallback time, the first penetration will be forced to proceed. The fallback time can be set in the range of 20 min to 40 min, for example, 30 min, to cover low water-cement ratio, high water retention and other low-bleeding formulation scenarios, ensuring that the test will start normally.

[0106] The identification and quantitative control of water seepage is achieved based on the grayscale threshold segmentation method: the acquired RGB image is converted into an 8-bit grayscale image, and the grayscale value of the dry mortar surface without water seepage is used as the benchmark threshold. The bright areas above the threshold are determined as water seepage areas, and the proportion of water seepage area to the total surface area of ​​the sample is calculated by pixel ratio.

[0107] The thickness of the bleed is determined by inversion using a grayscale calibration method. Different bleed thicknesses within the range of 0–2 mm are pre-calibrated under the same lighting and shooting conditions. The corresponding average gray value of the oozing area The linear relationship is obtained by fitting: ,in, The reference gray value for dry mortar. , These are calibration coefficients.

[0108] During the experiment, the average gray value of the bleed area is extracted and substituted into the calibration formula to calculate the average thickness of the bleed. The control module calculates the total amount of bleed based on the bleed area and thickness, matches the corresponding downward stroke of the suction drive rod, the power of the suction pump, and the working time, and drives the suction mechanism to quantitatively remove the bleed, ensuring thorough removal of the bleed while avoiding excessive pressure that could disturb the surface mortar structure.

[0109] After water absorption is completed, the system enters the automatic needle changing and penetration detection stage.

[0110] The automatic needle changing component automatically matches the standard penetration needle 42 with the corresponding cross-sectional area based on the penetration resistance value of the previous measuring point: a 100mm² large cross-sectional area needle is selected when the resistance is less than 3.5MPa, a 50mm² medium cross-sectional area needle is selected when the resistance is between 3.5MPa and 20MPa, and a 20mm² small cross-sectional area needle is selected when the resistance is not less than 20MPa, ensuring that the pressure sensor always works in the optimal range.

[0111] After the needle is changed, the drive motor 43 drives the penetration probe 4 to perform the penetration action. The composite control strategy of "speed PID closed loop + resistance feedforward compensation" is adopted to ensure constant penetration rate: the target penetration rate of 2.5mm / s is set as the set value, the actual speed fed back by the encoder in real time is the feedback value, and the basic torque value is output after PID calculation.

[0112] Simultaneously, the real-time penetration resistance collected by the pressure sensor is used as a feedforward disturbance, and the pressure is adjusted according to the pre-calibrated resistance-torque coefficient. The superimposed torque compensation amount compensates for the torque in advance when the resistance increases, offsetting the impact of sudden changes in resistance load on the speed, so that the penetration rate is kept stable within the range of 2.5mm / s±0.2mm / s throughout the process.

[0113] When the penetration depth calculated by the encoder reaches 23mm, the control mode switches from speed closed loop to position closed loop, and the motor speed is gradually reduced by using an S-shaped deceleration curve. The motor stops precisely at a depth of 25mm to avoid excessive penetration due to motor inertia. The depth control accuracy can reach ±0.5mm.

[0114] After a single-point test is completed, the displacement slide 41 moves the penetration probe 4 horizontally to the next test point. The system automatically plans the test point path to ensure that the distance between test points is not less than 15mm and the distance between the test point and the cylinder wall is not less than 25mm, while avoiding the disturbance area of ​​the previous test point. After the test point is switched, the sealing cover 12 automatically closes to retain moisture, waiting for the next test.

[0115] The detection interval is dynamically scheduled by the hydration heat temperature rise prediction model, and the model time axis is uniformly aligned with the timing zero point. .

[0116] The model uses an exponential hydration temperature rise function to describe the internal temperature development of the sample, and the function form is as follows: In the formula, The temperature inside the sample at time t is in °C. The initial temperature of the sample is expressed in °C. The peak temperature rise during hydration is expressed in °C. The hydration rate coefficient is... is the shape coefficient, and the other two are the parameters to be fitted.

[0117] Define hydration degree , which characterizes the relative progress of cement hydration reaction, and has a value range of 0 to 1.

[0118] Based on this, a power function relationship model between penetration resistance and hydration degree is established: In the formula, The penetration resistance at time t is expressed in MPa. As the reference drag coefficient, The resistance growth index is denoted by , and the other two are parameters to be fitted.

[0119] The model operation adopts a progressive fitting strategy, taking into account both early reliability and later accuracy: when there are less than 3 sets of effective penetration resistance data, the detection is performed at the default fixed interval according to the specification, that is, once every 30 minutes before initial solidification and once every 15 minutes after initial solidification. At the same time, the model continuously collects temperature rise data for pre-fitting and accumulates initial parameters; after accumulating 3 or more sets of effective penetration resistance data, it is officially switched to the temperature rise-resistance joint prediction mode.

[0120] The joint fitting process is as follows: First, the hydration temperature rise model is fitted using real-time collected temperature rise data to obtain... , , The initial value is used to calculate the degree of hydration at each time point; then, the degree of hydration at the corresponding time point and the measured resistance value are substituted into the correlation model to obtain the result. , With each new set of resistance data, all fitting parameters are updated simultaneously, enabling joint calibration of temperature rise data and resistance data, and the prediction accuracy gradually improves as the experiment progresses.

[0121] When predicting the setting point, the initial setting resistance threshold of 3.5 MPa and the final setting resistance threshold of 28 MPa are substituted into the resistance-hydration degree correlation model to calculate the corresponding critical hydration degree. Then, the critical hydration degree is substituted into the hydration temperature rise function to deduce the corresponding initial setting time and final setting time, and then the remaining time from the current setting point is calculated.

[0122] The interval for the next test is automatically adjusted based on the remaining time: when the predicted distance to the condensation point is greater than 2 hours, the test interval is set to 60 minutes; when the distance to the point is 1 to 2 hours, the interval is shortened to 30 minutes; and when the distance to the point is less than 1 hour, the interval is increased to 10 minutes. This strategy minimizes redundant measurement points in the early stage of hydration while ensuring accurate capture of the condensation inflection point, thereby reducing the frequency of mechanism actions and experimental energy consumption.

[0123] All data from the entire experiment are automatically stored in the storage unit. After the experiment, the control module 65 automatically fits and generates a complete resistance-time change curve. The initial setting time and final setting time are calculated from the zero point of water addition through linear interpolation. A standard format test report containing test parameters, environmental records, temperature rise curve, resistance curve, and setting time results is automatically generated and can be exported and saved through the data interface 61.

[0124] Those skilled in the art should understand that the above embodiments are merely for illustrating the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make other changes or modifications based on the above invention, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A fully automatic temperature-controlled concrete penetration resistance measuring device, characterized in that, It includes a frame, temperature control components, automatic insertion components, automatic needle changing components, automatic water suction components, standard trial mold components, and CNC device (6). The temperature control component is located inside the frame and includes a temperature control cavity (3) and a refrigeration unit, a heating unit, a humidification unit and a dehumidification unit disposed in the temperature control cavity (3); The standard test mold assembly is located in the temperature control cavity (3) and includes a standard penetration test mold (1), a test mold base (2) and a sample internal temperature sensor (13). The sample internal temperature sensor (13) is used to insert into the sample to collect the sample internal temperature. The automatic insertion assembly, the automatic needle changing assembly, and the automatic water absorption assembly are all located on the upper part of the frame and above the temperature control chamber (3); the automatic needle changing assembly is provided with multiple sets of standard insertion needles (42) with different cross-sectional areas. The numerical control device (6) is electrically connected to the temperature control component, the standard test mold component, the automatic penetration component, the automatic needle changing component and the automatic water absorption component, respectively. It is used to determine the detection time based on the internal temperature data of the sample and the measured penetration resistance data, and to control the automatic water absorption component to remove the water secreted on the sample surface, the automatic needle changing component to switch the standard penetration needle (42), and the automatic penetration component to perform the penetration detection at each detection time.

2. The fully automatic temperature-controlled concrete penetration resistance measuring device according to claim 1, characterized in that, The temperature control assembly also includes a temperature and humidity sensor (34) and a heat insulation layer (33). The temperature and humidity sensor (34) is located inside the temperature control cavity (3), and the heat insulation layer (33) covers the outside of the temperature control cavity (3). The refrigeration unit is a semiconductor refrigeration chip (31), and the heating unit is an electric heating component (32). The semiconductor refrigeration chip (31) and the electric heating component (32) are both attached to the outer wall of the temperature control cavity (3) and located between the temperature control cavity (3) and the heat insulation layer (33). The humidification unit is an ultrasonic humidification unit (36), and the ultrasonic humidification unit (36) and the dehumidification unit (37) are located on the side wall of the temperature control cavity (3).

3. The fully automatic temperature-controlled concrete penetration resistance measuring device according to claim 1, characterized in that, The standard mold assembly also includes an electromagnetic adsorption device (21). The standard penetration mold (1) is positioned on the mold base (2). The electromagnetic adsorption device (21) is fixed to the mold base (2) and electrically connected to the CNC device (6). The bottom of the standard penetration mold (1) is made of ferromagnetic material. When the electromagnetic adsorption device (21) is energized, it adsorbs and fixes the standard penetration mold (1) to the mold base (2). The measuring device also includes a sealing and moisturizing component, which includes a sealing cap (12) and a moisturizing cotton (11). The sealing cap (12) is used to cover the top of the standard penetration mold (1) during the testing interval, and the moisturizing cotton (11) is located inside the sealing cap (12).

4. The fully automatic temperature-controlled concrete penetration resistance measuring device according to claim 1, characterized in that, The automatic penetration assembly includes a drive motor (43), a displacement slide (41), a penetration probe (4), and a pressure sensor; The drive motor (43) is a servo motor and is located on the upper part of the frame; The penetration probe (4) is located below the drive motor (43) via the displacement slide (41) and is connected to the drive motor (43) in a transmission manner. The displacement slide (41) drives the penetration probe (4) to move horizontally to switch the measuring point; The pressure sensor is located at the lower end of the penetration probe (4); The automatic needle changing assembly further includes a needle changing turntable (44) and a needle changing drive (45). The needle changing turntable (44) is rotatably mounted on the frame, and the needle changing drive (45) is connected to the needle changing turntable (44) in a transmission connection. Multiple sets of the standard insertion needles (42) are arranged at circumferential intervals along the needle changing turntable (44); After the needle changing turntable (44) is rotated, the standard penetration needle (42) located at the working position docks with the penetration probe (4) and moves down with the penetration probe (4), while the other standard penetration needles (42) remain in a avoidance position.

5. The fully automatic temperature-controlled concrete penetration resistance measuring device according to claim 4, characterized in that, The automatic water absorption assembly includes a micro water pump (5), a water-absorbing sponge head (51), a water-absorbing drive rod (52), and an image acquisition module (7). The water-absorbing drive rod (52) is a lifting and telescopic structure. The water-absorbing sponge head (51) is located at the lower end of the water-absorbing drive rod (52). The micro water pump (5) is connected to the water-absorbing sponge head (51). The image acquisition module (7) is located on the upper part of the frame, facing the sample surface inside the standard penetration mold (1), and is electrically connected to the CNC device (6). The lens of the image acquisition module (7) is equipped with an anti-fog unit.

6. The fully automatic temperature-controlled concrete penetration resistance measuring device according to claim 1, characterized in that, The numerical control device (6) includes a control module (65), a touch panel (62), a pressure digital display (63), a temperature and humidity digital display (64), a real-time clock unit, a storage unit, and a data interface (61). The touch panel (62), the pressure digital display (63), and the temperature and humidity digital display (64) are located on the front of the frame. The real-time clock unit is used to calibrate the test time reference with the time of cement mixing and water addition as the zero point of timing; the storage unit is electrically connected to the control module (65), and the data interface (61) is connected to the storage unit.

7. A fully automatic temperature-controlled concrete penetration resistance measurement method, implemented using the fully automatic temperature-controlled concrete penetration resistance measurement device as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. The sieved mortar sample is placed into the standard penetration test mold (1) and fixed in position. The internal temperature sensor (13) of the sample is inserted into the sample, and the time of mixing cement and water is taken as the zero point of timing. S2. Adjust the ambient temperature and humidity in the temperature control chamber (3) to the set value and maintain it stable, while collecting the internal temperature data of the sample. S3. Determine the timing of each test based on the internal temperature data of the sample and the measured penetration resistance data, and execute the test sequentially at each testing time: Remove the oozing water from the sample surface; Select a standard penetration needle (42) with the corresponding cross-sectional area based on the measured penetration resistance. Drive the penetration probe (4) to drive the selected standard penetration needle (42) to penetrate the sample at a constant speed and collect the penetration resistance; Move to the next measurement point; S4. Fit the resistance-time curve based on the time and penetration resistance data obtained from each test, and calculate the initial setting time and final setting time.

8. The fully automatic temperature-controlled concrete penetration resistance determination method according to claim 7, characterized in that, In step S2, the target absolute moisture content is determined based on the set target temperature and target relative humidity; During temperature regulation, the target absolute moisture content is used as the control benchmark. The current saturated vapor pressure and corresponding relative humidity are determined based on the current temperature. The outputs of the humidification unit and the dehumidification unit are adjusted to counteract the relative humidity drift caused by temperature changes.

9. The fully automatic temperature-controlled concrete penetration resistance measurement method according to claim 7, characterized in that, In step S3, determining the time of each detection includes: The first test uses a dual-condition triggering method, which acquires the sample surface image and identifies the water seepage state. When the water seepage reaches the preset triggering condition, the first test is started. If the preset triggering condition is not met even after the time from the zero point of the timing has reached the preset fallback time, the first test is forcibly started. If the number of penetration resistance data sets obtained after the first test is less than the preset number, the test will be performed at a preset fixed interval. After the number of penetration resistance data sets reaches the preset number, a hydration temperature rise model is fitted based on the internal temperature data of the sample and the degree of hydration is determined. A correlation model between penetration resistance and degree of hydration is established. The initial setting resistance threshold and the final setting resistance threshold are substituted into the correlation model to back-calculate the corresponding setting point time. The interval of the next test is adjusted according to the remaining time from the current time to the setting point time.

10. The fully automatic temperature-controlled concrete penetration resistance measurement method according to claim 7, characterized in that, In step S3, the removal of oozing water from the sample surface includes: Acquire a sample surface image, determine the bleed area and bleed area from the sample surface image based on grayscale segmentation, determine the bleed thickness based on the grayscale value of the bleed area and the pre-calibrated grayscale-thickness relationship, determine the bleed amount based on the bleed area and the bleed thickness, match the water absorption execution parameters based on the bleed amount, and remove the bleed water according to the water absorption execution parameters; The uniform penetration adopts a control method that combines speed closed-loop and resistance feedforward. The speed closed-loop control is performed with the target penetration rate as the set value, and the drive output is compensated with the real-time collected penetration resistance. When the penetration depth reaches the preset switching depth, the speed closed-loop is switched to the position closed-loop and the speed is reduced until the target penetration depth is reached.

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